title: Production of cloned dogs by decreasing the interval between fusion and activation during somatic cell nuclear transfer.
abstract: To improve the efficiency of somatic cell nuclear transfer (SCNT) in dogs, we evaluated whether or not the interval between fusion and activation affects the success rate of SCNT. Oocytes retrieved from outbred dogs were reconstructed with adult somatic cells from a male or female Golden Retriever. In total, 151 and 225 reconstructed oocytes were transferred to 9 and 14 naturally synchronized surrogates for male and female donor cells, respectively. Chromosomal morphology was evaluated in 12 oocytes held for an interval of 2 hr between fusion and activation and 14 oocytes held for an interval of 4 hr. Three hundred seventy-six and 288 embryos were transferred to 23 and 16 surrogates for the 2 and 4 hr interval groups, respectively. Both the male (two pregnant surrogates gave birth to three puppies) and female (one pregnant surrogate gave birth to one puppy) donor cells gave birth to live puppies (P > 0.05). In the 2 hr group, significantly more reconstructed oocytes showed condensed, metaphase-like chromosomes compared to the 4 hr group (P < 0.05). A significantly higher pregnancy rate and a greater number of live born puppies were observed in the 2 hr group (13.0% and 1.1%, respectively) compared to the 4 hr group (0%) (P < 0.05). In total, three surrogate dogs carried pregnancies to term and four puppies were born. These results demonstrate that decreasing the interval between fusion and activation increases the success rate of clone production and pregnancy. These results may increase the overall efficiency of SCNT in the canine family.
authors.affiliation: SooAm Biotech Research Foundation, Wonsam-myeon, Cheoin-gu, Yongin-si, Gyeonggi-do, South Korea.
authors.forename: Sue
authors.initials: S
authors.lastname: Kim
authors.forename: Sun Woo
authors.initials: SW
authors.lastname: Park
authors.forename: Mohammad Shamim
authors.initials: MS
authors.lastname: Hossein
authors.forename: Yeon Woo
authors.initials: YW
authors.lastname: Jeong
authors.forename: Joung Joo
authors.initials: JJ
authors.lastname: Kim
authors.forename: Eugine
authors.initials: E
authors.lastname: Lee
authors.forename: Yeun Wook
authors.initials: YW
authors.lastname: Kim
authors.forename: Sang Hwan
authors.initials: SH
authors.lastname: Hyun
authors.forename: Taeyoung
authors.initials: T
authors.lastname: Shin
authors.forename: Woo Suk
authors.initials: WS
authors.lastname: Hwang
mesh_terms: D000818:Animals; D019976:Cloning, Organism; D003627:Data Interpretation, Statistical; D004285:Dogs / Q000235:genetics* / Q000502:physiology; D046149:Embryo Culture Techniques / Q000379:methods / Q000662:veterinary*; D004622:Embryo, Mammalian / Q000502:physiology* / Q000648:ultrastructure; D005260:Female; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D053652:Nuclear Transfer Techniques / Q000662:veterinary*; D009865:Oocytes / Q000502:physiology; D011247:Pregnancy; D018873:Pregnancy Rate; D013997:Time Factors